Recently, several advertisers have withdrawn their advertisements from

OFFICIAL EXPLANATION:

This is GMAT Pill CR Framework #4 Exclusive Negation

The argument is that "morality" was the only thing governing the advertiser's decision to withdraw their ads from the magazine.

So the framework says to put it like this:
Argument: "morality" --> exclusively leads to --> withdraw ads
Negation: "other factors" --> did not affect --> withdraw ads

(C) brings up a factor "financial reasons" and discounts financial reasons as a possible factor in affecting the decision to withdraw ads. If withdrawing ads was a financial BENEFIT, then they may have decided to withdraw ads based on financial reasons. But (C) clearly states that by withdrawing, there would be a financial DISBENEFIT. As a result, it cannot possibly be the case that "financial reasons" (an example of "other factors") affected the decision to withdraw ads.

(C) is an example of the negation and thus helps strengthen. GMATPill Framework #4 Exclusive Negation successfully conquers this question.

With (D) signing up for other publications that value family -- this does not necessarily mean they did it for moral reasons. They may have done it for financial reasons primarily. (D) works but (C) is stronger.